48 University of California Publications in Geology [Vol. 13 



elements with this ramus. Among these bones was an incomplete 

 skull from the "Crag," near Antwerp. Subsequently, Rutten 19 based 

 his Trichechus mitverpieusis upon "la tete d'Alachtherium" of Van 

 Beneden, which he assumes was wrongly associated with the lower 

 jaw which Du Bus had made the type of Alachthcrium cretsii. Rutten 

 called attention to the fact that several peculiar modifications in the 

 fragmentary skull made articulation impossible with this mandibular 

 ramus. More recently Hasse 20 concluded that all previous descriptions 

 of fossil walruses were based on such faulty material that they should 

 be disregarded. Following this assumption, Hasse proposed the name 

 Alachtherium antwerpiensis for a nearly complete cranium unearthed 

 during recent excavations in the Antwerp basin. The descriptions 

 and comparisons given by Hasse are more accurately and carefully 

 drawn up than those of any previous author. A critical study of these 

 diagnoses and an examination of the figures shows that the walrus of 

 Hasse was undoubtedly the same as Rutten 's Trichechus autverpiensis. 



In this same Pliocene sea there existed a quite different type of 

 walrus which was contemporaneous with Alachtherium. This form 

 was named Trichecodon huxleyi by Lankester 21 and was based upon 

 portions of several tusks from the Red Crag of Sutton, Felixstow, 

 and Bawdsey, Suffolk County, England. Previous to this account of 

 Lankester, fossil tusks of walruses from these same beds had been 

 identified as either the ponderous tusks of Dinotheriuin or of Masto- 

 don. A few years later, Van Beneden 22 redescribed Lankester 's form 

 as Trichecodon koninckii. His description is based on a portion of a 

 tusk which Nyst discovered. Van Beneden also associated with this 

 tusk other skeletal elements which were acquired later from various 

 points in the Antwerp basin. In this description Van Beneden men- 

 tions the tooth from Russia figured by Eiehwald 23 and states that it 

 should be referred to this genus. Later 24 he says it is hardly probable 



20 Hasse, G., Les Morses du Pliocene Poederlien a Anvers. Bull. Soe. Beige de 

 Geol., de Paleont. et d'Hydrol., Brussels, Mem., vol. 23, pp. 293-321, pis. 3-6. 

 1910. Les sables noirs dits Miocenes bolderiens a Anvers, op. ext., Proces Verbal, 

 vol. 23, pp. 353-361. 1910. Une defense de morse dans le Pliocene a Anvers, 

 op. tit., Proces Verbal, vol. 25, p. 172. 1912. 



21 Lankester, E., Trichecodon huxleyi, a new mammalian fossil from the Eed 

 Crag of Suffolk. Quart. Jour. Geol. Soc. London, vol. 21, pt. 3, no. 83, pp. 226-231, 

 pi. 10, figs. 1-3, 5, 6, and pi. 11, fig. 1. 1865. 



22 Van Beneden, P. J., Les Phoques de la mer scaldisienne. Bull. Acad. Roy. 

 Sci. de Belgique (2), vol. 32, na 7, pp. 12-17, pi. 3. 1871. 



23 Eiehwald, E., Lethaea Rossica, ou Paleontologie de la Russie, vol. 3, p. 390. 

 Stuttgart, 1853. 



Van Beneden, P. J., Description des ossements fossiles des environs d 'Anvers. 

 Ann. Mus. Roy. Hist. Nat. de Belgique, Brussels, vol. 1, pt. 1, p. 53. 1877. 



